Electronically controlled air bag systems for automotive vehicles are generally known in the prior art. Conventional electronically controlled air bag systems typically comprise a collision sensor attached to the vehicle body, an ignition device which receives an output signal from the collision sensor and an inflator which is ignited by the ignition device and which provides a sufficient amount of gas in a short amount of time to expand an air bag. The air bag is usually mounted on the steering wheel so as to prevent the driver of the automobile from sustaining injuries in the event of a collision.
In conventional air bag systems, main components including the air bag, the inflator and the ignition device are assembled together in a module, and are installed on the steering wheel as a unit. To install the air bag module, it is necessary to connect one or more electrical harnesses between the module and the steering wheel before bolting the module to the steering wheel. Such a system is shown, for example, in Japanese Laid Open Patent Application No. 63-184546.